Parallel optical communications modules include parallel optical transmitter modules, parallel optical receiver modules and parallel optical transceiver modules. A typical parallel optical transmitter module includes a plurality of laser diodes for generating optical data signals, laser diode driver circuitry for driving the laser diodes, and a controller for controlling operations of the transmitter module. A typical parallel optical receiver module includes a plurality of photodiodes for receiving optical data signals, receiver circuitry for demodulating and decoding the received optical data signals, and a controller for controlling operations of the receiver module. Parallel optical transceiver modules typically include the components described above of the transmitter module and of the receiver module.
In many parallel optical communications modules, openings exist in the modules through which airborne dust, dirt, gases, or other particulates may enter the module. Ingress of such airborne matter into the module can sometimes cause problems in the modules. For example, ingress of dust into a part of the module that contains the laser diodes can potentially block light output from the laser diodes or received by the photodiodes, which, in turn, can lead to performance issues. Some modules have relatively open designs that enable them to be assembled at lower costs and that facilitate the evaporation of moisture in the modules. Therefore, while an open module design can be beneficial, such designs are susceptible to problems associated with the ingress of dust, dirt, gases and other airborne matter. In addition, some modules are required to pass mixed flow gas (MFG) tests, during which a module is placed in a chamber and exposed to aggressive chemical gases, such as fluorine and chlorine, for example. These gases can find their way into a module and erode metal components of the module (e.g., bond wires, conductors, etc.), thereby causing damage to the module that can lead to performance problems.
A need exists for a parallel optical communications module that has protection against ingress of airborne matter such as dust, dirt, gases, and other airborne particulates that can harm the components of the module and/or interfere with the optical path of the module.